386 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



As a result of investigations a set of typical specifications for non- 

 bituminous road materials was prepared for publication as a depart- 

 ment bulletin. This bulletin, in general, conforms to the recom- 

 mendations of the first conference of State Highway Testing En- 

 gineers and Chemists, and it is believed will do much toward further- 

 ing standardization of specifications for such materials. Forty indi- 

 vidual specifications arje given, covering brick, gravel, mineral filler, 

 Portland cement, sand, sand-clay, slag, stone, stone block, top soil, 

 and total mineral aggregate for various types of road. Each speci- 

 fication is followed by a brief description of the suitability of the 

 material for a given purpose. The bulletin also contains methods 

 for testing the materials for conformity to the specifications and 

 directions for sampling. 



The survey of quarry conditions in the United States has been con- 

 tinued in the Middle West and South. About 170 quarries have so 

 far been studied. 



The following subjects are under investigation: The suitability of 

 various types of soil for the construction of bituminous soil roads; 

 the standardization of screening practice in the production of 

 crushed stone ; and the use of slag in road construction. 



STANDARDIZATION OF METHODS OF TESTING BITUMINOUS ROAD MATERIALS. 



Cooperative work with the American Society for Testing Materials 

 was continued, and as a result a number of standard methods and 

 definitions were recommended to the society for adoption. Improve- 

 ments were made upon an apparatus originally devised by the office 

 for accurately determining the consistency at normal temperature of 

 road oils and tars used in the surface treatments of macadam and 

 gravel roads. Cooperative work will be continued with the Ameri- 

 can Society for Testing Materials in connection with a number of 

 standard tests and specifications. 



STANDARDIZATION OF METHODS OF TESTING NONBITUMINOUS ROAD MATERIALS. 



As a result of cooperation with Committee D^ of the American 

 Society for Testing Materials, various standard tests, methods, and 

 definitions were recommended to the society for adoption. Investiga- 

 tions have been continued and are now in progress upon the follow- 

 ing subjects: Revision of the standard abrasion test for rock, the 

 standardization of an abrasion test for gravel, the development of 

 new tests for paving brick and concrete. 



CONCRETE INVESTIGATIONS. 



Concrete investigations during the past year have been mainly 

 confined to cooperation with the United States Shipping Board in 

 determining the resistance to shear of various structural members 

 used in concrete ship designs; also in the protection of reinforce- 

 ment from the action of sea vv^ater with reference to disturbing as 

 little as possible the bond between reinforcement and concrete. A 

 number of inspections were made of concrete construction. 



